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I have Todd Down's book "Bicycle Repair and Maintenance." He says the rear Derailler should be removed, and the outside grit cleaned off with diesel fuel. I used kerosene. I brushed off the grit - I did not soak it.

I am going to relube all pivot points with Tri-Flow. The main spring in the knuckle(?) housing was coated with a clearish grease. Do I need to regrease that spring, or can I just coat it with Tri-Flow? All I have is axel grease, and it seems that that would attract grit.

In other words, I cleaned the derailler without disassembling it. How should I relube it?
Thanks

A small amount of something like tri-flow at the pivots would be good. The spring just needs lube to prevent rust - not critical what kind of lube. Are the pulleys funky? You might want to take them apart and clean them and, again, use sparing amounts of lube. In my suburban/urban riding derailleurs never get funky enough to require heavy duty degreasers, just a good wipe down.

To avoid grit from making an end-run into the mechanism, apply the lube you choose drop-wise on, and only on, the moving parts. The temptation is to add more lube than is truly needed. Overcome this. It's when you do add it where it's not needed, the derailleur acts like a magnet for grit & grime. The other contender for being at fault is the chain. When it needs oil, once again, add drop-wise to each pivot. Practice Zen and the art of oiling. And always wipe off the excess - if there is any.

Most dry lubes are either parafin wax based or use a light binder to retain teflon powder. In both cases the carrier solvents for these will allow the new lube to mix with the old and over time as the lubes go away and need to be refreshed then there will be less and less of the motor oil and more and more of the other stuff.

So bottom line is just give'r a wipe and wash it if there's grit and apply the new stuff.

For my own needs that involve riding a lot in the rain I just use motor oil or my beloved chain saw bar oil which is a lot thicker so it doesn't run. I tried some of the "dry" lubes years ago and found that unless used far more frequently than grease and oil that they didn't protect against rusting worth a damn. Depending on the local climate YMMV. But really if used sparingly there is nothing at all wrong with motor oil. It's a great lube that seems to suffer only from a stigma of being "too easy and too common". There's really very little, if anything, that the specialty stuff does any better.

My own favourite witch's brew is the thick chain saw bar oil mixed 50-50 with mineral spirits. Goes on thin so I can wipe away the excess and dries over a day or to so a nice thin film that doesn't run or wash away in the rain easily.

I'd call this a job for: Gumout. Unless another solvent it handy, Gumout is widely available and contains toluene. It's an excellent solvent for old grease & oil. Just use it in a well-ventilated area or it will get you so high you'll be dancing with the Leprechuan you didn't know was living in your shop-area.

Once clean and dry, proceed to lube the derailleur (and whatever else) with your chosen lube.

Whenever I'm rebuilding an old bike, I always pull the DRs off and thoroughly clean and relube them. The idlers are almost always filthy with built-up lube and gruck, and I always take the cage apart and lube the plain bearings inside. Better DRs will have a high-quality ceramic bearing (bushing, actually) on the top idler...Don't forget where it goes.